Why C++ over Rust? I’m genuinely asking, not trying to evangelize.
My biggest issue with C++ is that although it does seem to be adding lots of good quality of life changes with the recent standards for developers it has inherit flaws that without breaking backwards compatibility it can never be as safe as Rust. And I think C++ is probably right to not break backwards compatibility, it has too large of a user base that will most likely splinter, it reminds me of the python 2/3 problems.
At this point, it appears that Rust could well survive and become a mainstream language, eventually, but that is by no means assured. While that puts it well ahead of any other language created in this millennium, it is very far from ready to raise a family on.
Remember, Ada had far more investment and industry backing than Rust will have for a long time to come, but was wiped out. Fighter planes are coded in C++, not Ada.
Rust is used by, and financially supported by, many of the learning companies in the technology industry: Microsoft, Google, Facebook, AWS, Dropbox, and others. It's being piloted for use in the Linux kernel and is already accepted into Android.
Unlike Ada, its development was never bootstrapped by public funds and so all of its growth is due to its practical benefits.
I don't know why fighter planes are the standard to reach, but Rust is even being used in aerospace: both Rocketlab and SpaceX have made public statements supporting Rust or are hiring people with Rust expertise.
"Used by <Big Company>" means much, much less than most people who mention it believe. The bigger the company, the more likely it is that they use literally anything at all you can think of, and the correspondingly less it means that they do. They might even be using it in a certain project deemed strategic. But we all know how many of even "strategic" projects at big companies end up canceled, even when they seemed to be a success. You can be certain that they are not using it for anything central to how the company makes its money.
It is more interesting when a $company uses $newtech where it will only have an income if the project succeeds. But you probably never heard of $company, otherwise, so have no way to evaluate how important it is.
SpaceX has said publicly it uses C++ for mission-critical work. Like other $billions companies, they do a lot of things. Saying they do Rust, too, makes them seem edgy in circles where people are likely to hear about it, regardless of how much they actually depend on it. So it is really hard to tell.